WASHINGTON — The White House is weighing direct military strikes to stem an Islamic militant group’s gains in Iraq, as well as humanitarian relief for thousands of displaced religious minorities in the country’s north, according to U.S. defense officials and others familiar with the administration’s thinking. President Barack Obama huddled with his national security team today morning to discuss the crisis as the Islamic State group made further gains. Airstrikes in particular would mark a significant shift in the U.S. strategy in Iraq, where the military fully withdrew in late 2011 after nearly a decade of war. Officials said Obama could announce a decision as early as today. In recent days, the Islamic State militants have swept through villages in the north that are home to religious minorities including Christians and the Yazidis, who follow an ancient religion with ties to Zoroastrianism. Furthering their gains, the extremists seized Iraq’s largest dam today, placing them in control of enormous power and water resources and access to the river that runs through the heart of Baghdad. While the White House did not publicly outline the range of options under consideration, officials said the U.S. strongly condemns the extremists’ assault on minorities.